The present invention relates to the field of detecting the presence of frost and/or of measuring the thickness of frost by ultrasound.
At the present time magneto-striction probes and pressure probes are utilised to perform a qualitative detection of frost on the wings of an airplane. These probes have the drawback of disturbing the flow of air around the wing and of necessitating the placing in operation of movable parts, which are hence fragile, whence a diminution in the reliability of the detection systems.
In the field of measurement of the thickness of the frost layer, it is known to use optical or optoelectronic probes which have however the main drawbacks of necessitating the use of transparent walls, generally of glass and hence fragile, and especially of being limited to the measurement of small thicknesses. Hyperfrequency probes are also known which have the drawbacks of requiring complex equipment and of necessitating careful adjustments; in addition, calibration of them is delicate and, generally, they are better adapted to the detection of the presence of frost than to the measurement of its thickness. Finally, vibrating probes are known of which the disadvantage is of being fragile and of being limited to the measurement of small thicknesses of frost (typically 5mm).
In addition, it is well known to use ultrasonic vibrations to analyse materials, in particular to measure the thickness thereof, and attempts have been made to detect the presence and/or to measure the thickness of frost. However, the known devices do not provide information exploitable in real time.
In brief, none of the types of probes at present known, both of the detection of the presence of frost and for the measurement of its thickness, gives total satisfaction.